Approximately 9% of children in the United States live with an alcoholic or drug dependent parent (U.S. Department of Health and Human Services, 2001). Children whose parents primarily abuse drugs other than alcohol often display emotional and behavioral problems (e.g., Fals-Stewart, Kelley, Fincham, Golden, & Logsdon, in press; Kelley & Fals-Stewart, 2002; Sowder & Burt, 1980; Wilens et al., 2002). Men are more likely to abuse substances (including marijuana, hallucinogens, and heroin) than are women (Department of Health and Human Services, 2002), and data suggest that the number of men with children seeking substance abuse treatment may outnumber the number of women two to one (U.S. Department of Health and Human Services, 2003); however, studies have focused on prenatal effects or postnatal exposure to maternal drug abuse. Because of our long-standing programmatic line of research (couples-based treatments for drug-abusing adults), we have systematically collected extensive longitudinal data (i.e., pretreatment, posttreatment, 6- month, and 12-month follow-up) as part of five NIDA or private foundation grants on parenting, biological-genetic, family, and dyadic variables, and the emotional and behavioral functioning of custodial school-aged children living with drug-abusing fathers. We propose to conduct a large-scale secondary analysis of data collected from parents, children, and children's teachers who took part in the five projects. This study will provide a rare opportunity to delineate parenting, genetic, family, and dyadic factors that may be risk or protective factors for children, and to establish how different treatments for parents change parent and family functioning and impact children (i.e., the mechanisms of action that result in secondary child benefits). This will provide much-needed information that will be used to inform future multifaceted treatments for drug-abusing parents and their children.